The present invention relates to a remote control system for video display apparatus, and more particularly to a remote control system having a position-dependant transmitter, an electrooptical loop which controls the motion of a cursor on a television screen, adaptive filters, forming a part of the electrooptical loop, which stabilize the position of the cursor o on the screen, and a menu controller which generates menu entries for selecting functions for tuning and operating the television receiver.
Remote control devices provide a convenient means for controlling video display apparatus such as television sets, video recorders and personal computers. Because the video display apparatus typically contains a large number of tuning and operational functions, remote control can become complicated, especially from a distance. To control the large number of functions required by the video display apparatus, an interactive mode is provided in which a user selects the desired function from a succession of menus. Each menu provides symbols and fields which correspond to functions such as volume. The user simply selects the desired function by positioning the cursor within a field.
The position of the cursor is typically controlled by the remote control device. One such remote control system is disclosed by application Ser. No. 07/450,971, filed by Heberle on 12/15/89 and assigned to ITT Corporation, which is entitled "ELECTROOPTICAL POINTING DEVICE FOR REMOTELY CONTROLLING ELECTRONIC APPARATUS" and which is incorporated herein by reference. There, an electrooptical arrangement determines the relative motion of a cursor on a television screen by evaluating the relative angular positions of a transmitter in different reference planes with respect to a reference line between the transmitter and the television receiver. The transmitter is formed by three sources of radiation whose signals are emitted along three parallel optical axes. Each axis determines a reference plane. Two sources have rising/falling radiation patterns. The third source, which provides a reference signal, has a flat radiation pattern. The electrooptical arrangement, located at the front of the television receiver, detects the radiation patterns, determines tilting of the transmitter by evaluating the relation between signal intensities of the three . radiation patterns, and generates reference signals which correspond to the tilt angles in the vertical or horizontal directions. Thus, the combined evaluation of the two directions of tilting permits continuous motion control in any direction on the screen. Analog functions can be controlled by the relative motion of the cursor. For instance, a slider control for volume is displayed symbolically by a bar. To increase or decrease volume, the bar is either lengthened or shortened by the motion of the cursor.
Since the position of the cursor is dependant upon the motion of the transmitter, it becomes apparent that an unsteadiness in the hand of a user has a negative effect on the cursor position. A resulting high frequency jitter of only a few hertz causes the cursor to jump around the screen. Even if in small excursions, this jitter prevents the user from positioning the cursor precisely within a field on the screen. The prior art has approached this problem by increasing the area of the field for each menu entry. However, this method has the unwanted effect of reducing the number of functions available on the screen. Alternately, a lowpass filter is employed to suppress the high frequency jitter. However, a lowpass filter degrades the overall performance of the remote control since the cursor follows the course adjustment sluggishly.